Extensible stand



Oct. 8, 1946. A. M. sTARcK EXTENSIBLE STAND Filed Nov. 18, 1944 R o T NE V m ORNEYS Patented Oct. 8, 1946 UNITED. STATES PATENT OFFICE ArthurM. Starck, Stamford, Conn.

Application November 18, 1944, Serial No. 564,110

2 Claims. (Cl. 248-161) This invention relates to adjustable stands andmore particularly to stands for lamps, microphones, music supports andthe like.

Stands for lamps and the like have been made vertically adjustable byvarious constructions which usually employ clamping screws that have thedisadvantage of requiring loosening and tightening each timeit isdesired to change the height adjustment. Screws are furthermoredifficult to operate and detract from the appearance of the stand. Theunbalanced weight of the vertically movable part of a stand causesconsiderable eifort to be required to raise it and also makes itdifiicult to obtain accurate adjustment.

Principal objects of the present invention are to provide an improvedstand for'lamps and the like which is easily adjustable in height, whichneeds only to be pushed down or up to adjust its height, and which willremain at the adjusted height without the use of clamping screws. Otherobjects of the invention are to provide an adjustable stand of the typein which the upper portion is vertically movable with respect to thelower portion; in which the Weight of the upper portion iscounterbalanced; in which the counterbalancing device is completelyenclosed within telescoping tubular members of the.stand; and in which aspring is employed as a counterbalancing element in such a manner thatthe variation in force exerted by the spring may be compensated.

Other objects of the invention will in part be obvious and will in partbecome apparent from the following detailed description of oneembodiment thereof, in which:

Figure l is an elevational view of an exemplary lamp stand according tothe invention, with parts broken away to show the interior construction;

Figure 2 is a view of a section taken on the line 2-2 of Figure 1showing the upper anchor of the counterbalance device;

Figure 3 is a view of a section taken on the line 33 of Figure 1 showingthe counterbalance and means to prevent relative rotation betweentelescoping members;

Figure 4 is a view of a section taken on the line 44 of Figure 1 showingthe guide between the spiral ribbon and the spring; and

Figure 5 is a view of a section taken on the line 5-5 of Figure 1showing the lower anchor of the counterbalance device.

As a preferred example the stand device of the present invention isincorporated in a floor lamp or bridge lamp. The device to be supportedis 2 embodied in a lamp in secured in a customary manner at the endof across arm ll of a post 12 which is mounted on top of an upper telescopetube I3. The tube l3 telescopes within a lower tube M which has an innerdiameter onlyslightly greater than the external diameter of the tube [3.The tube 14 is vertically supported by suitable means such as a base 15.It is desirable to provide means for preventing relative rotationbetween the tubes [3 and I4 and for such purpose a spline orlongitudinal ridge [6 is formed in the wall of the tube l3 and acorresponding cooperating groove is formed in the tube 4,

The function of the counterbalance deviceis to stabilize the weight ofthe movable part of the stand, that is, the tube l3 and the partssupported thereon. The counterbalance device is disposed entirely withinthe tubes 13 and i4, and it includes a helical torsion spring I! havingits lowerend secured by a bolt l8 to the lower end of the tube [4. Aspacer I9 is disposed between the Wall of the tube l4 and the spring [1.The spring I! extends to a point near the upper end of the tube l4 andhas secured to its upper end a cap piece 20 by engagement of the uppercoils of the spring in threads 2| formed in the cylindrical part of thecap. In the upper portion of cap 20 there is provided a slot-shapedopening 23 the longer dimension of which is substantially equal to theinner diameter of the cylindrical part of the cap piece.

Through the slot 23 extends an auger-like or ribbon-like spiral member24 such as may be formed by twisting a rectangular flat strip of metal.The twist or pitch of the spiral however, is not uniform for reasonshereinafter described. The length of the spiral member 24 is slightlygreater than the length of the spring l1 and it extends upward into thetube I3 to which it is anchored at its upper end. A stud 25 is securedto the inside wall of the tube [3 and the end of the stud is threaded toreceive a nut 26 which clamps the upper end of the member 24 to thestud. When the member 24 is forced into the spring H, the cap 20 isrotated and such rotation twists the spring I'I. When the member 24 andtube l3 are stationary, the tension of the spring I! reacts on thehelical elements or surfaces of the member 24 and tends to force itupwardly. The pitch of the member 24 and the strength of the spring [1are selected so that the upward force on the member 24 is sufficient tobalance the weight of the tube I3 and elements carried thereby.

When a torsion spring is twisted, its tension Thus when the cap 2011s inthe upper region of the member 24; the coarse pitch in conjunction withthe greater tension of the spring l'l will pro; vide an upward thrust inmember 24 which is about the same as the upward thrust which is obtainedby the weaker tension in conjunction with the finer pitch when the capZlldsizithelower region of the member 24. I

While not essential, it is' found'advantageous to enclose the spring I!within a guide tube. 23 in which the cap 20 and spring I! are rotatableand which is secured between the spacer l9 and the endof the spring H bybolt [8. A limited degree 7 of adjustment of the counterbalance deviceaccording tothe weight to be supported is obtainable by preset ns h i ital te s on of the spring ll as by givingthe lower end the requisitenumber of turns-before securing it by the bolt I8 7 It will be seen thatthe lamp may bemoved up and down with equal. ease, that such movementwill be smooth, and that only a minor amountof friction between themovable and stationary parts sufiices to hold the lamp firmly in y a u tpos tion.

nder toq j ha e clo u described above, various, modifications may bemade without affecting the. principle of theinvention; furtherthattheinvention is not to be n dered s l mi d t h e m ntwh h 4 is describedherein only for purposes of illustration, but solely by the terms of theappended claims.

What is claimed is:

1. In a telescoping stand having stationary and movable relativelynon-rotatable portions, a device for counterbalancing the weight of themovable portion, said device comprising a helical compression springnon-rotatably, secured at one endto' the stationary portion, a capmember rigidly secured to the other end of said spring, and an elongatedmember non-rotatably secured at one end to the movable portion andprovided with a helical element extending through and threadedlyengaging said cap member to torsion said spring, aid cap member reactingunder the torsional force of said spring to provide a verticalforce'adapted to support the weight of said movable portion.

2; In a telescoping stand having stationary and movable relativelyvnon-rotatable portions, a. device for counterbalancing the weight of themovable portion, said device comprising a helical compression springnon-rotatably secured at one end to the stationary. portion, a capmember rigidly secured to theother end of said spring, and an elongatedmember non-rotatably secured at one end to the movable portion andprovided with a helical element extending through and threadedlyengaging said cap, member to torsionsaid spring, said cap memberreacting under the torsional force of said spring to provide a verticalforce adapted to support the weight of said movable portion, saidelement having a variablepitch, said pitch being greatest at the endfarthest removed from the spring and least at the end which enters thespring.

ARTHUR; M. STARCK.

